Abstract: In order to improve medium recovery,the problems of dilute medium processing system of middlings and gangue in Wangfenggang coal preparation plant was analyzed. The process was transformed based on coal properties. The gangue was easy to degrade in water,so there was a large number of high- ash fine slime which was difficult to settle. The slime led to high- ash products,low calorific value,large treatment capacity of system and poor circulating water. The transformation was that separating middling and gangue dilute medium,treating the magnetic tailings by adding cyclone and sieve bend. After transformation,the ash of middlings reduced by 4. 5% and the calorific value increased by 1. 51 MJ / kg. The raw coal revenue increased by RMB 2. 44 per ton,the plant increased economic benefits by RMB9 × 106 one year.